Image analysis – Applications – Biomedical applications
Reexamination Certificate
1999-03-22
2001-07-17
Johns, Andrew W. (Department: 2621)
Image analysis
Applications
Biomedical applications
Reexamination Certificate
active
06263093
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a three-dimensional ultrasound image processing apparatus and a coordinate transformation method used in the apparatus, and more particularly to a three-dimensional ultrasound image processing apparatus which forms a three-dimensional ultrasound image based on three-dimensional image data obtained by scanning a three-dimensional region and a coordinate transformation method used in the apparatus.
2. Description of the Prior Art
Three-dimensional image processing apparatuses include various kinds of apparatuses such as a three-dimensional ultrasound image processing apparatus and a three-dimensional X-ray image processing apparatus. A three-dimensional ultrasound image processing apparatus has the function of acquiring three-dimensional echo data and the function of processing thus acquired three-dimensional echo data (hereinafter, the “three-dimensional echo data” is also referred to simply as “three-dimensional data”).
More specifically, according to the three-dimensional image processing apparatuses, a scanning plane (two-dimensional data acquiring region) is formed by electronic scanning using an array transducer having a plurality of transducer elements, and a three-dimensional data acquiring region (space) is formed by successively forming numbers of such scanning planes with displacing (pivotally swinging or rotating) the array transducer. The three-dimensional echo data obtained from this three-dimensional data acquiring region is sent to a three-dimensional image processing circuit via a signal processing circuit. Then, by reconstructing the three-dimensional echo data, a three-dimensional ultrasound image for the three-dimensional data acquiring region is formed. Such a processing is also performed in a three-dimensional X-ray image processing apparatus.
Now, in a conventional three-dimensional ultrasound image processing apparatus, each of echo data for the three-dimensional echo data acquiring region is temporarily stored in a three-dimensional echo data memory which has a storage region corresponding to the three-dimensional data acquiring region. In this case, each of the echo data is represented by the three-dimensional polar coordinates in which each data is defined by the depth r of the data on the ultrasound beam, the angle &thgr; of the ultrasound beam relative to the scanning start position (beam) in the scanning plane and the displacement angle &PHgr; of the scanning plane. Therefore, when the echo data is to be stored in the three-dimensional echo data memory, each of echo data is subjected to a coordinate transformation by which the three-dimensional polar coordinates are transformed into the three-dimensional orthogonal coordinates (X, Y, Z). In other words, each of echo data is stored in an address of the memory specified by the three-dimensional orthogonal coordinates, and thus stored echo data will be reconstructed to form the three-dimensional image.
However, such transformation of the three-dimensional polar coordinates into the three-dimensional orthogonal coordinates requires a large amount of arithmetic operations, and such an increased operational amount causes a problem in that it takes a long time for processing the data. In this connection, it is naturally preferable to make the time from data acquisition to image display as short as possible, and if feasible, it is desired to display the three-dimensional image in real time. In order to resolve such a problem, it may be possible to reduce the time for arithmetic operations through the use of a high speed processor or the like. In such a case, however, there arises other problem in that the cost for the image processing apparatus is markedly increased.
Moreover, in forming such a three-dimensional ultrasound image, it is necessary to carry out interpolation between ultrasound beams (lines) and interpolation between scanning planes (frames). However, execution of these interpolations for the data for the three-dimensional coordinate space also requires, a large amount of arithmetic operations as stated in the above. This also makes it difficult to shorten the time for arithmetic operations.
Further, it is to be noted that the above problems are not limited to the case of a three-dimensional ultrasound image processing apparatus, and other three-dimensional image processing apparatuses also involve such problems.
SUMMARY OF THE INVENTION
The present invention has been made in view of the problems described above. Therefore, an object of the present invention is to provide a three-dimensional image processing apparatus which can perform writing of three-dimensional data to a three-dimensional data memory in a short time and at a high speed.
Another object of the present invention is to provide a three-dimensional image processing apparatus which can produce a three-dimensional image through a reduced amount of arithmetic operations.
Other object of the present invention is to provide a three-dimensional image processing apparatus which can perform interpolation of three-dimensional data in a short time and at a high speed.
In order to achieve the above objects, the present invention is directed to a three-dimensional ultrasound image processing apparatus. The apparatus comprises:
three-dimensional data acquiring means which forms scanning planes successively by ultrasound beam scanning to acquire three-dimensional data for a three-dimensional data acquiring region, each three-dimensional data being specified by two dimensional data represented by first and second values defining each scanning plane and relative positional information of the scanning plane with respect to a predetermined scanning plane;
two-dimensional coordinate transformation means for transforming the first and second values for the respective scanning plane into two-dimensional data represented by two-dimensional coordinates (x, y);
two-dimensional data storage means for sequentially storing the two-dimensional data for the respective scanning plane with one scanning plane as a unit, in which the two dimensional data for the respective scanning plane is written into an address specified by the two-dimensional coordinates (x, y) determined by the two-dimensional coordinate transformation means;
three-dimensional coordinate transformation means for transforming the three-dimensional data defined by the two-dimensional data represented by the two-dimensional coordinates (x, y) and the relative positional information of the respective scanning plane into three-dimensional data represented by three-dimensional coordinates (X, Y, Z), in which the two-dimensional coordinate x is made to correspond to the three-dimensional coordinate X;
three-dimensional data storage means for storing the three-dimensional data for each of the scanning planes which is defined by the two-dimensional data represented by the two-dimensional coordinates (x, y) outputted from the two-dimensional data storage means and the relative positional information of each scanning plane, in which the three-dimensional data for each scanning plane is written into an address specified by the three-dimensional coordinates (X, Y, Z) determined by three-dimensional coordinate transformation means; and
three-dimensional ultrasound image producing means for producing a three-dimensional ultrasound image based on the three-dimensional data outputted from the three-dimensional data storage means.
According to this three-dimensional ultrasound image processing apparatus, two-dimensional data (two-dimensional echo data) defining the respective scanning plane are temporarily written into the two-dimensional data storage means (intermediate storage) with each scanning plane as a unit, rather than being written directly into the three-dimensional data storage means. In this case, the address (x, y) to be written is generated by performing coordinate transformation in the two-dimensional coordinate transformation means. The amount of the arithmetic operations required for the coordinate transformation
Aloka Co., Ltd.
Johns Andrew W.
Marger & Johnson & McCollom, P.C.
Nakhjavan Shervin
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